1. Field of the Invention
The present invention relates to a band saw machine in which the action of sawing a workpiece is produced by means of an endless band saw blade which runs on both a driving wheel and a driven wheel. Specifically, the present invention relates to a band saw machine wherein it is possible to automatically revise the allowable value for the deviation of cut in proportion to the width of the workpiece to be cut; to detect the when the band saw blade comes off the driving wheel or off the driven wheel; to easily replace a rotating wire brush for brushing off the sawdust adhering to the band saw blade; to cover the exposed section of the band saw blade for safety; to automatically feed the workpiece material repeatedly and to detect the fact that the workpiece has become shorter than a fixed dimension when fixed dimension cuts are being carried out on the workpiece; and to smoothly discharge the sawdust or chips produced by the action of sawing the workpiece, from inside a box-shaped base.
2. Description of the Prior Art
In the well-known horizontal type of band saw machine, a main body vise device for securing the workpiece is provided on a box-shaped base which supports a workpiece which is to be sawn. A freely elevatable cutting head is mounted on this base, and both a driving wheel and a driven wheel, on which runs an endless band saw blade for sawing the workpiece, are supported in a freely rotatable and removable manner on this cutting head. Furthermore, in a horizontal-type of band saw machine, a deviation detecting device for detecting the deviations from the vertical cutting line in the workpiece by detecting the amount of distortion of the band saw blade, and a rotating wire brush for brushing off the sawdust adhering to the band saw blade when the workpiece is being sawn, are provided as standard equipment.
In addition, in a horizontal band saw machine which automatically performs a fixed dimension cut on the workpiece, a control means to automatically control the elevation of the cutting head is provided, while a feed vise device for repeating the fixed dimension feeding of the workpiece is provided, which device can freely advance or retreat and placed on the rear section of the main body vise device. In addition, in an automatic horizontal band saw machine, a screw conveyor is provided for discharging from the box-shaped base to the outside the sawdust produced when the workpiece is being sawn.
In any event, in a conventional horizontal band saw machine, the device for detecting the amount of the deviation of the vertical cutting line in the workpiece must be reset by hand for the allowable value for the deviation of the cutting line each time the width of the workpiece to be cut is changed. Accordingly, the relationship between the width of cut and the allowable value for the deviation of the cutting line in the workpiece must be recorded for future reference in a graph or table, and each time that the width of the workpiece to be cut changes, the allowable value for the deviation of the cutting line must be set making reference to the graph or table. This is an extremely troublesome operation.
In addition, in a horizontal band saw machine, when the depth of cut of the band saw blade into the workpiece is excessive, slippage occurs between the band saw blade and the driving wheel, and there is a tendency for the band saw blade to come off the driving wheel. Conventionally, a type of device which detects any change in speed of rotation of the driven wheel has been commonly used as a device to detect when the band saw blade comes off the driving wheel. However, the problem exists that the construction of such a conventional device is extremely complicated, resulting in high cost manufacturing.
In addition, in a horizontal band saw machine, a rotating wire brush is provided for cleaning off the sawdust which adheres to the blade of the band saw when the workpiece is being sawn. However, in a conventional horizontal band saw machine, the operation of replacing this rotating wire brush is not very simple, which is a troublesome problem.
Furthermore, in conventional horizontal band saw machine there is the problem that the band saw blade is exposed in the space between the band saw blade guide member which guides the band saw blade between the driving wheel and the driven wheel, and the housing section which houses the driven wheel, causing a dangerous situation.
In addition to this, in a horizontal band saw machine which automatically feeds the workpiece material at a fixed dimension or length, a feed material vise device which freely advances or retreats, feeding the material at a fixed dimension, after arriving at a previously established position, detects the fact that the workpiece has become shorter than the fixed cut dimension. Specifically, in this conventional machine, after the feed vise device retracts to the set position, a movable vise jaw provided on the feed vise device is operated to grasp the workpiece. Then by detecting whether or not the abovementioned movable vise jaw touched the workpiece, detection is made to determine whether or not the workpiece has become shorter than the fixed cut dimension. Accordingly, a long time is required conventionally until the detection is made as to whether or not the length of the workpiece is adequate. Also, there is the problem that, at the time when the workpiece becomes shorter than the fixed cut dimension, the workpiece can fall into the space between the main body vise device and the feed vise device.
Further, in a conventional horizontal band saw machine, when the sawdust produced by sawing the workpiece is discharged from the inside of the box-shaped base by the screw conveyor, the sawdust little by little gathers into large lumps which become attached to the rotating shaft of the screw conveyor, making it difficult to discharge this sawdust in shape of large lumps. Accordingly, the sawdust adhered to the screw conveyor must occasionally be removed, which is a troublesome operation.